Sea mink description

The last known specimen of sea mink was taken in 1880 from an island in the Gulf of Maine, and this is the year attributed to the species’ final extermination (2). Little is known about this large species of mink, as extinction occurred before any scientific study was undertaken. The sea mink is reported to have had a long, bushy tail which would have been about a third of its body length and was densely covered in coarse, reddish-brown fur. Almost 50 percent larger in length than its closest relatives, the sea mink was also broader and more robust, most likely an adaptation to cope with the bitterly cold temperatures of the Atlantic Ocean (3). Females are thought to have been smaller than males, a common mustelid trait, although for the sea mink this can only be predicted from the size of skull bones excavated in recent years from Native American shell middens(4).

Related species

Sea mink biology

Initially, the sea mink was believed to be one of the many subspecies of the extant American mink (Mustela vison); it was only after its extinction that the sea mink was recognised as a species in its own right. This was due mostly to its impressive size and the structure of its teeth, which were better adapted to a different food source, implying it had diverged to inhabit a distinct ecological niche(4). The sea mink is recognised as one of the most aquatic of all the mustelids, excluding only the otters (4). Similar to the others mustelids, the sea mink would have been a voracious predator, although its diet was probably more specialised than other species in the Mustelagenus, consisting mostly of fish, seabirds and their eggs, and molluscs. Despite minks being thought to have poor underwater eyesight, it is believed that much of this animal’s time would have been spent in the ocean, hunting its preferred prey (4).

Little is known about the social behaviour of the sea mink, but other species in the Mustelagenus are characterised by a solitary, nocturnal existence. All minks are territorial but males are particularly aggressive towards other males. Each male defends a linear territory usually extending a few kilometres along a river bank or shoreline, and several female territories may overlap with a male’s but one male’s territory will never extend into another male’s. Scent marks signal an individual’s presence and trespassing usually results in violent conflicts (7). Both sexes are promiscuous and mate with several partners during the months of April and May, with males tending to roam from their territory to seek more partners. The blind, hairless and helpless young tend to be born after a gestation period of about 34 days, although it may last up to 70 days as delayed implantation often occurs. The litter of five to ten young stays with the mother until 13 to 14 weeks of age; however, the step to independence and finding a territory is usually fraught with dangers and high mortality (7).

Sea mink range

The exact range of the sea mink is debated, but general consensus suggests it occupied a region extending along the Atlantic Coast of North America from Massachusetts to Nova Scotia, possibly including Newfoundland (5).

Species with a similar range

Sea mink habitat

Rocky-shored coastal regions and offshore islands were the preferred habitats of the sea mink, as they would have provided shelter from predators and the elements, as well as easy access to food sources, which would have been particularly important for females with young, dependent kits (6).

Species found in a similar habitat

Sea mink status

Sea mink threats

The sea mink was hunted to extinction, a victim of unregulated removal and killing to support an expanding European fur market. Even before European arrival, Native Americans were already capturing and utilising the pelts and most likely the meat of the minks, although the less intensive hunting by these people would not have depleted the population to a level that was unsustainable (2)(6). The low numbers of surviving infants would have been a contributing factor as to why the sea mink was unable to survive the pressures of the fur trade (7). Much can be learnt from the extinction of this small mammal; most important is the need for strict regulation in the numbers of animals removed from a population in harvests.

Glossary

The process of a fertilised egg remaining unattached in the uterus for a period of time, therefore delaying the start of development.

Ecological niche

The role a plant or animal plays in its community. It is defined by the way it interacts with other living things and the physical environment, such as where it lives, what it eats, and its predators.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Gestation

The state of being pregnant; the period from conception to birth.

Molluscs

A diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.

Mustelid

A family of carnivores with short, stocky legs, an elongated body and long, sharp canine teeth. Includes otters, weasels, ferrets and badgers.

Nocturnal

Active at night.

Shell middens

Midden is a term used by archaeologists to describe a feature containing waste products relating to day-to-day human life. Shell middens are comprised mainly of mollusc shells, such as clams, oysters and mussels, indicating their consumption by prehistoric people.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

Territorial

Describes an animal, a pair of animals or a colony that occupies and defends an area.

Territory

An area occupied and defended by an animal, a pair of animals or a colony.

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